The present invention relates generally to telephone switching systems, and in particular, to a method for recovering emergency calls in a switching system at an operator station during an operator position failure.
The public telephone network is designed to provide assistance to callers in emergency situations. The public telephone network has specialized switching equipment to route emergency calls to a regional center of operators who process the calls and initiate the dispatch of services needed in an emergency. Emergency calls are typically initiated by dialing a special number. Then, the operator connects the call to an emergency authority. The emergency authority handles the dispatch of emergency units such as the paramedics, police and firefighters. The operator typically remains on the call until the emergency authority tells the operator to release the call.
Telephone switching systems are known to monitor the integrity of the switching system and associated resources. The switching systems periodically perform a battery of tests to detect position failures at operator stations or other errors within the switching system. For example, switching systems typically detect system failures when an operator has no functionality at the operator station, when communication links or trunks are malfunctioning, or when there is a hardware failure with a switching module. However, the switching system is not equipped to retrieve and reconnect emergency calls that were connected to the operator stations at the time of the position failures.
In existing switching systems, if a position failure occurs while an emergency call is at the operator station, the operator is logged out and the call is lost or dropped and the operator position is gradually torn down (i.e., data structures associated with the operator position are cleanly eliminated). This can occur before or after the operator connects to the emergency authority. Presently, there is no established method to recover emergency calls at failed positions. Of course, this is not desirable due to the importance of any single emergency call.
Therefore, a need exists for a method to recover emergency calls at an operator station during a position failure.
A method is provided for recovering emergency calls at an operator station during a position failure. First, an operator station receives a call. After receipt of the call, if a position failure occurs at the operator station, the position failure is detected. Then, a determination is made as to whether the call is an emergency call. For example, the sequence of called digits is compared to a predetermined sequence of digits to determine if the call is an emergency. If the call is an emergency call, then a determination is made as to the status of the call. The status of the call includes determining whether the call has any extraneous connections, whether the operator connected the call to an emergency authority, whether the call is active or on hold, and whether the call is at subscriber initiated or operator initiated. Based on the status of the call, the call is connected to an available operator station by performing a call transfer, a float, a one-party recall, or a two-party recall.
A system for recovering emergency telephone calls includes a first operator station, a second operator station and a switching system. The switching system is coupled to the first operator station and the second operator station. The first operator station receives calls. The switching system monitors the status of the first operator station. If the switching system detects a failure with the first operator station, the switching system determines whether the calls connected to the first operator station are emergency calls. If the calls are emergency calls, then the switching system determines a status of the calls and connects the calls to the available second operator station. By reconnecting emergency calls at a failed first operator station with an available second operator station, emergency calls are not disconnected from a caller and emergency calls are handled expediently.